1. Technical Field
The present invention relates to a liquid ejecting head and a liquid ejecting apparatus, and in particular, to an ink jet recording head and an ink jet recording apparatus that discharge ink as the liquid.
2. Related Art
In an ink jet recording head, which is a typical example of a liquid ejecting head, in general, ink is supplied from an ink reservoir unit filled with ink, such as an ink cartridge, to a head main body, and the ink supplied to the head main body is discharged from a nozzle by driving a pressure generator, such as a piezoelectric element or a heater element.
In such an ink jet recording head, when air bubbles present in ink in an ink cartridge or air bubbles mixed in the ink during attachment or detachment of the ink cartridge are supplied to a head main body, discharge failure due to the presence of the air bubbles, such as dot missing, occurs. In order to solve this problem, in a known ink jet recording apparatus, a filter for removing, for example, air bubbles in ink is provided in an ink channel disposed between an ink cartridge and an ink jet recording head, a part of the ink channel being formed by an ink supply needle, which is inserted into the ink cartridge (see, for example, JP-A-11-10904, p. 2 and p. 3, FIG. 1).
The formation of this filter can prevent air bubbles from flowing in a head main body. However, it is difficult to discharge air bubbles accumulated in the filter section.
To solve this problem, another known ink jet recording apparatus includes a bypass channel for bypassing a filter chamber disposed upstream of a filter and a supply channel disposed downstream of the filter so as to discharge air bubbles accumulated in the filter section through the bypass channel (see, for example, JP-A-9-141890, p. 3 and p. 4, FIGS. 2 to 4).
However, in the structure disclosed in JP-A-9-141890, ink also flows through the bypass channel without passing through the filter. Accordingly, foreign matter such as contaminant matter cannot be trapped by the filter, resulting in a problem of clogging of a nozzle, or the like. In addition, when large foreign matter flows in the bypass channel, the bypass channel clogs and does not function. Furthermore, the bypass channel described in JP-A-9-141890 is used for discharging air bubbles. Accordingly, in a state in which air bubbles are accumulated on the filter, supply failure of ink occurs, and the frequency of discharging the air bubbles accumulated on the filter cannot be reduced. Therefore, unnecessary waste of the ink cannot be reduced.
These problems occur not only in ink jet recording heads that discharge ink but also in other liquid ejecting heads that eject a liquid other than ink.